Every big bad in Kingdom Hearts is either a Xehanort or somebody similar to him in personality. We need a villain who doesn’t side with Light or Darkness, one who just wants to see the world go mad. It could really shake the villain hierarchy to have an antagonist who just wants to laugh at his own chaotically evil deeds. Also I don't mean a pre existing character with this kind of mindset (even though Kefka or Bill Cipher as a boss fight would be cool). I mean a new antagonist